[A case of non-small cell lung cancer with EGFR mutation responding to S-1 after a therapy with gefitinib].

A 78-year-old man had underwent right upper lobectomy for lung adenocarcinoma in July 1998(pT1N0M0, pStage Ia). In January2003, computed tomography showed a tumor in right lower lobe of lung, which grew slowly. He was treated with UFT. In April 2004, computed tomographyshowed multiple nodules in both lung, which was considered of metastasis of lung cancer. The increase of the nodules were observed, and treatment with gefitinib was started. Insertion mutation at EGFR in exon 20 was seen from the primarylung cancer. Since tumor growth occurred despite gefitinib administration, we converted gefitinib into S-1 using 80 mg/day for 28 days, followed by 14 days rest. Chest computed tomographyshowed a partial response. No side effect was observed, and continued internal use of S-1 until January 2007 when it was impossible to continue, and meanwhile, the increase of the tumor was not seen.